If proven safe and effective in people, the antibody drug could be given to at-risk pregnant women to prevent brain damage to their babies, the scientists say.

Zika virus derived from a pregnant woman was used to infect eight monkeys. Half the monkeys were infused with the drug, the rest were left untreated. None of the treated monkeys became infected, but all of the untreated monkeys did.

The drug is a “cocktail” of three Zika-neutralizing antibodies Scripps Research scientists found in a South American patient. These are manufactured as monoclonal antibodies, selected for their potency and for their combined ability to block any mutational escape by the mosquito-borne virus.

Study results were published Thursday in the journal Science Translational Medicine. David I. Watkins of the University of Miami and Dennis R. Burton of The Scripps Research Institute led the study. It can be found at j.mp/zikadrug.

The study is significant because it extends results previously seen in mice to primates, said virus researcher Sujan Shresta, an associate professor at the La Jolla Institute for Allergy & Immunology.

“The fact that they don’t see any virus is a great sign, and I really like the concept of giving three different monoclonals, because these viruses are always mutating,” Shresta said. “Giving three different antibodies that recognize three different targets on the virus is important.”

Shresta cautioned that more studies are needed, especially in people, to confirm the cocktail will be of use.

Mapp has also been assisted by The Scripps Research Institute, one of the country’s top centers of viral research. In addition to Zika and Ebola, Scripps Research scientists are studying how to protect against HIV, influenza and other major health threats.

Zika virus is spread by the Aedes aegypti species of mosquito. That mosquito has been found in San Diego County, but it is much less prevalent than in southern Texas and Florida. The main centers of infection are in South America, especially Brazil.

Zika infection runs an unpredictable course. Many people experience few to no symptoms during infection. They recover without incident and may not even know they were infected. A few become seriously ill with neurological complications, and some die.

But while Zika is generally only a moderate threat to adults, it’s extremely dangerous before birth, when it is prone to attack developing fetal brain tissue. Affected babies are born with unusually small brains, or microcephaly. This can cause lifelong developmental disabilities, seizures and other neurological complications.

People who recover from Zika are immune to re-infection for an unknown period of time. The body’s immune system produces antibodies that neutralize the virus, as they do with the much deadlier Ebola virus.

The study said pregnant women are good targets for antibody therapy because it’s safe and well understood. It’s possible to engineer antibodies so one dose prevents infection for more than six months. Thus, therapy can be directly given to those most in need of it.

Antibodies delivered by infusion have the disadvantage that they only protect as long as they are present; they don’t confer immunity like that produced by an infection or by vaccination. So giving them to a large population would be less efficient than giving a Zika vaccine. None have been approved, but they’re under development.

However, the study said technical obstacles will delay making vaccines against Zika and other related viruses, called flaviviruses. Inadequate production of antibodies could actually make the infection worse. And some antibodies against one virus could cause harmful cross-reactions to infection by another.

Moreover, pregnant women may not demonstrate the needed immune response to a vaccination. These obstacles could take years to solve, the study said.

The Food and Drug Administration has launched a crackdown on clinics hawking stem cell treatments for a range of ailments. (September 1, 2017) (Sign up for our free video newsletter here http://bit.ly/2n6VKPR)

The Food and Drug Administration has launched a crackdown on clinics hawking stem cell treatments for a range of ailments. (September 1, 2017) (Sign up for our free video newsletter here http://bit.ly/2n6VKPR)

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Researchers used eggs from healthy females and the sperm of a man who carried a gene mutation that causes inherited hypertrophic cardiomyopathy. (Aug. 3, 2017) (Sign up for our free video newsletter here http://bit.ly/2n6VKPR)

Researchers used eggs from healthy females and the sperm of a man who carried a gene mutation that causes inherited hypertrophic cardiomyopathy. (Aug. 3, 2017) (Sign up for our free video newsletter here http://bit.ly/2n6VKPR)